Maintaining inflatable tires on wheel rims while permitting the tire to be readily removed from the rim for repair or replacement has presented many problems over the years. To properly maintain a tire in place on the wheel during use, a bead bundle is provided in the rim-engaging portion of the tire. This bead bundle enhances the tire's rim gripping capacity and helps maintain the tire on the rim. The rim-engaging portion of the tire with the bead bundle is generally known in the art as the tire bead. In an unstressed condition, the inner diameter of the tire bead is smaller than the diameter of the rim on which it resides.
The small clearance between the tire and the rim makes removing tires from their rims difficult. A variety of hand tools such as slide bars, hammers, chisel-like tools, and jackscrews have been used to disengage the tire bead from the rim of a wheel. These techniques typically require great strength and dexterity on the part of the operator. Furthermore, these hand tool techniques can cause damage to the tire and rim.
The process of disengaging the tire from the rim of a wheel is frequently referred to as “bead breaking”. After the tire bead is broken, the tire may then be stripped from the rim of the wheel. Many of today's tires and, in particular, the All Terrain Vehicle's (ATVs) tire designs have further complicated the task of bead breaking. Because ATVs are designed for off-road driving over rough, slippery and even soft, muddy surfaces, the tires upon which they ride are typically wide, soft, and balloon-like.
These tires operate at low inflation pressures, typically approximately 3-5 psi because the rough terrain typically traversed by an ATV when driven aggressively can unintentionally break the tire bead, generally because of side loads imposed upon the tire. To solve the problem, safety rims were developed having an additional annular safety rib offset from the rim to provide additional support for the tire bead. These safety ribs effectively prevent the tire beads from breaking away from the rim, particularly when the tire is subjected to a side load. While the use of such safety rims has largely eliminated bead breaking problems with ATV tires, it has led to a new problem.
Intentionally breaking the bead of a tire mounted to a safety rim is difficult. The balloon-like profile of the tires used on ATVs makes it difficult to insert a tool between the rim and the tire. The bead does not readily yield to simple inward pressure, which is otherwise sufficient to break the bead of a tire on a non-safety rim. Even conventional “tire-changing” machines disposed in garages, tire store, etc. are not readily usable to break the bead of a typical ATV tire. This is in part because such machines are designed to deal with tire sizes found on passenger vehicles and small trucks.
Because, as their name implies, ATVs are typically operated far from a road, often traveling cross-country over rugged terrain, a flat tire is highly problematic. Many ATV operators can recite tales of long walks out of the woods carrying a vehicle rim bearing a flat tire.